Embodiments of the invention relate to sensors and methods for the detection of gaseous agents, and more particularly to materials and sensors for the detection of chlorine dioxide, hydrogen peroxide, formaldehyde, peracetic acid, methyl bromide, ethylene oxide, ozone, and other gaseous agents that can be used as sterilization, fumigation, or decontamination agents.
Decontamination, fumigation, and sterilization of different environments is critical for a diverse range of applications including healthcare, food safety, and animal safety, for example. A number of gases can be used for the purposes of sterilization, fumigation, and decontamination including, but not limited to, chlorine dioxide, formaldehyde, hydrogen peroxide vapor, peracetic acid, methyl bromide, ozone, and ethylene oxide. These gases, as well as others, are known to be effective against both spore and non-spore forming bacteria.
Detection of gaseous agents that are utilized for decontamination, fumigation, and sterilization is critical for overall safety. It is beneficial to determine the presence of sterilizing agents to ensure that a given agent is performing adequately and that the surface or material being sterilized is free of harmful contaminants. For instance, measuring the presence of vapors by discerning a change in certain environmental variables within or surrounding a sensor may be particularly useful in monitoring changes in biopharmaceutical products, food, or beverages; monitoring industrial areas for chemical or physical hazards; security applications, such as residential home monitoring or home land security in airports; different environmental and clinical settings; and other public venues wherein detection of certain harmful and/or toxic vapors may be particularly useful. While current sensors offer a wide variety of both battery free and wireless sensors, there exists a commercial need for a reversible, battery-free sensor that requires no electrical contact with a sensor reader. Moreover, it is desired to have a sensor able to exhibit multiple responses to a change in an environmental parameter to eliminate sensor arrays.
The resistance change provided by semiconducting metal oxides when exposed to a vapor, for example, is either an up or down change. Traditionally, sensor arrays that include multiple sensors for functional and accurate monitoring are utilized. Many sensor arrays include a number of identical transducers coated with different sensing materials. However, while using identical transducers simplifies fabrication of the sensor array, such an array may have limited capabilities for sensing only a single response (e.g. resistance, current, capacitance, work function, mass, optical thickness, light intensity, etc). In certain applications, multiple responses or changes in multiple properties may occur. In such applications, it may be beneficial to include an array of sensors wherein different transducers in the array employ the same or different responses (e.g. resistance, current, capacitance, work function, mass, optical thickness, light intensity, etc.) and are coated with different sensing materials such that more than one property can be measured. Disadvantageously, however, fabricating a sensor array having individual sensors uniquely fabricated to sense a particular response complicates fabrication of the array and is uneconomical. Therefore, a single sensor that comprises a sensing material that can simultaneously exhibit more than one response when in the presence of an analyte is desired.
Various embodiments disclosed herein may address one or more of the challenges set forth above.